1. Field of the Invention
The invention relates to a method and apparatus for making a composite article having a substrate component and a soft trim component.
2. Background Art
Vehicle interior door panels or other interior plastic components often have a hard, plastic substrate component and a soft trim component. The soft trim component can be manufactured from a PVC film, TPO and foam film, or a soft foam polyurethane that is applied to the substrate in a second process step. In the latter case, in order to provide the soft trim component with a desired surface texture and color, a separate skin material is carefully applied to the molded foam and then trimmed to provide the article with the desired xe2x80x9cshow surface.xe2x80x9d Alternatively, the separate skin material is carefully positioned in the mold tool before the foam is injected into the mold, with the excess skin material and any foam bleed thereafter being trimmed to obtain the finished article. This trimming of the skin results in a substantial waste of skin material, which adds further cost to the process.
In order to avoid the costly trimming operation after foam molding, U.S. Pat. No. 5,736,082 teaches a method for foaming a composite article wherein the substrate surface includes a recessed portion to which the foam is to be applied, such that the recessed portion includes peripheral side walls; and a skin member is carefully placed within the mold opposite the recessed portion of the substrate such that a series of raised xe2x80x9cside wallsxe2x80x9d defined on the skin member are fitted in the substrate""s recessed portion when the mold is closed. Upon injection of a polyurethane foam composition into the mold, the foam expands to force the side walls of the skin member against the peripheral side walls of the substrate""s recessed portion, thereby effecting a peripheral seal to retain the foam material behind the skin material and, hence, avoiding a requirement for a subsequent trimming operation. Unfortunately, in order for the side walls of the skin material to perform the sealing operation, the skin member must be precisely placed within the mold cavity because a failure to obtain the desired seal will likely cause the foam material to bleed onto the show surface of the article, resulting in an unusable part and lower production yields. Moreover, the skin material must necessarily be more substantial in order for its side walls to remain raised during its placement in the mold and the subsequent mold closure, thereby further increasing material costs associated with the article.
Accordingly, what is needed is a method and apparatus for making a composite article including a substrate and an over molded soft trim component that reduces or eliminates a post-mold trimming operation in which manufacturing and materials costs are reduced, and production yields increased, without loss of quality, feel, or appearance.
Accordingly, it is an object of the invention to provide an improved method of making a composite article having a soft, overmolded trim component that reduces or eliminates the need to trim the overmolded component after the overmolding step.
It is a further object of the invention to provide a method of making a composite article wherein an overmolded foam component is mechanically locked and, preferably, also chemically bonded with a substrate.
Under the invention, a method of making a composite article having a soft trim component includes applying an in-mold coating onto at least a first mold cavity surface defined by a pair of mold halves, wherein the first mold cavity surface is contoured to define a shape and a surface texture of the soft trim component. The method further includes inserting, between the pair of mold halves, a substrate having a first surface including a first area, a second surface, and an aperture defining a closed path from the first area of the first surface to the second surface, wherein inserting includes positioning the first area of the first surface in opposition to the in-mold coating on the first mold cavity surface such that a gap is defined between the first surface of the substrate and the in-mold coating; and injecting a foam through the aperture into the gap. Because the foam is gated through the second surface, for example, a rear surface of the composite article opposite its xe2x80x9cshow surface,xe2x80x9d the invention beneficially eliminates the need for trimming the gate generated during foam injection.
In accordance with a feature of the invention, applying the in-mold coating includes spraying the in-mold coating onto the first mold cavity surface. And, under the invention, the in-mold coating may beneficially define a colored, show surface on the composite article while a grained first mold cavity surface imparts a desired grained surface texture to the article""s resulting soft trim component.
In accordance with another feature of the invention, the foam and the material of the substrate are preferably selected such that the injected foam forms a chemical bond with the substrate while the portion of the foam gate extending through the substrate""s aperture further serves to mechanically interlock the overmolded foam to the substrate. In a variation of the method, the step of injecting the foam includes bleeding the foam onto the second surface of the substrate to thereby further mechanically lock the foam to the substrate.
In accordance with yet another feature of the invention, the substrate preferably includes a second area immediately adjacent to the first area, and the first one of the mold halves includes a mold portion defining a peripheral edge of the first mold cavity surface; and further including seating the mold portion against the second area before injecting. Preferably, the material of the substrate has a first hardness, and wherein the mold portion includes a layer of a sealing material having a second hardness greater than the first hardness. Moreover, when the mold halves are brought together immediately prior to the foam injecting step, the mold portion of the first mold half preferably coins the second area of the substrate to thereby further improve the seal between the mold portion and the substrate. As a result, the bleeding of injected foam during the injecting step out of the first mold cavity is effectively eliminated, thereby also reducing or eliminating the need for trimming the soft trim component along the interface between the first and second areas of the substrate""s first surface.
Other features, advantages and benefits of the invention will be apparent from the following description, including the accompanying Drawings.